Hydrogen chloride-aluminum chloride hydrocarbon conversion processes



M 1945' w. A. PRELL ETAL 2,382,814 I HYDROGEN CHLOR-IDE-ALUMINUM CHLORIDE HYDROCARBON CONVERSION PROCESSES Filed Dec. 15, 1941 2 sheets-sheet 1 2,382,814 HYDROGEN HLORIDE-ALUMINUM CHLORII'DE 'HYDROGARBON CONVERSION PROCESSES 2 Sheets-Sheet 2 w Nmr w. A. PROLL r-:TAL

Filed Dec. 15, 1941 \wh\ @NN A L ww NNN C@ Nwnnwm, Y RN.

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Patentedl Aug. 14, 1945 uNlTED STATES PATENT oFFicE HYDROGEN CHLORIDE-AL CHLO- ama mmnocAnBoN coNvERsloN Pnoo- ESSES- Wayne A. Proell, Chicago, Ill., and Frank K. Ovitz,

Whiting, Ind., assignors to Standard Oil Company, Chicago, Ill., a corporation of Indiana Application December 15, i941, Serial No. 422,988

Claims.

- ride to such conversion processes or systems. A

further object is to provide a new and improved unitaryiconversion system for both generating and utilizing hydrogen chloride. A further object is to avoid the necessity of purifying. pumping, transporting, or otherwise handling the hydrogen chloride required for aluminum chloride hydrocarbon conversion processes, such as isomerization.

iA further object is to provide an improved light naphtha isomerization system wherein make-up hydrogen chloride may be supplied by chlorine gas without detriment to the catalyst activity or to the quality of the resulting isomerization products. A further object is to produce valuable by-products from hydrocarbon oils and waxes as an adjunct to a light naphtha isomerization process. A further object is to provide a unitary system of hydrogen chloride generation and utilization wherein impurities may be removed from the generated hydrogen chloride after it is introduced into the isomerization system but before it reaches the isomerization step of the system.

A further object is to provide an improved method and means for utilizing the hydrogen chloride which has heretofore been a waste product in the petroleum industry. Other objects will be apparent as the detailed description of our invention proceeds We will describe our invention as it is applied to a system for isomerizing paraiiinic hydrocarbons of the C4 to Ce boiling range. In this .system the charging stock absorbs hydrogen chloride from one or more gaseous streams under superatmospheric pressure within the general vicinity of 50 to 350 pounds per square inch, preferably in the general vicinity of 200 pounds per square inch. The charging stock-hydrogen chloride solution is then passed througha heat exchanger to an isomerization reactor wherein it is contacted with an aluminum chloride catalyst, preferably in the form of an aluminum chloride hydrocarbon complex, at a temperature within the approximate range of 100 to 450 F., preferably 200 to 300 F.,

' and at a pressure within. the approximate range of 500 to 1500 pounds per square inch, for example about 850 pounds per square inch. Gases are separated from reaction products and returned to the absorber for recovering hydrogen chloride for reuse but a considerable amount of hydrogen chloride is actually consumed in the process and must be either continuously or intermittently supplied thereto.

Chlorine is much less expensive and more easily handled than hydrogen chloride and chlorine gas may be introduced directly into the isomerization reactor or into the products entering said reactor for supplying the necessary hydrogen chloride;

this expedient, however, is not desirable because' the resulting isomerization products may be characterized by a lower octane number and because the catalyst apparently loses its activity much more rapidly when chlorine gas is introduced than when hydrogen chloride is introduced into the isomerization system.

In practicing vour invention we generate the hydrogen chloride from chlorine or other chlorine supplying reagent and a hydrogen supplying re.- agent in a generator which forms a unitary part of the isomerization system and which discharges directly into the hydrogen chloride absorber in said system so that there is no necessity of employing any compressors for handling the hydrogen chloride gas and therev is no necessity of removing hydrocarbons or other impurities from the generated hydrogen chloride gas. The hydrogen chloride absorber in the isomerization system serves the double function of removing undesirable gasesfrom recycled gas streams and simultaneously removing undesirable gases from the generated hydrogen chloride.

Any type of hydrogen chloride generator may where R is a hydrocarbon radical oi 1 to 50 or more carbon atoms. This converts about half of the introduced chlorine into hydrogen chloride and produces chlorinated hydrocarbons which may be employed as by-products for various uses. Additional hydrogen chloride may be vobtained from the chlorinated hydrocarbon by the addition of a dechlorination catalyst such as aluminum chloride, barium chloride, iron chloride and the like either to give olens in accordance with the reaction (where R' `is unsaturated hydrocarbon) or to give polymers,.condensation products, alkylation products, or the like in accordance with the general equation:

RC1+RH- RR+HC1 1n accordance with our invention any one or more of the above reactions are employed under superatmospheric pressure sufcient to permit the generated hydrogen chloride to be injected directly into the isomerization reaction system.

Heretoiore when hydrocarbonsI have beenr conjunction with Athe. accompanying drawingsVl which form a part of the vspeciication and-ln which Figure 1 is a diagrammatic yflow sheet of the isomerization system of which our hydrogen chloride generator is an integral part, and

Figure 2 is a schematic flow diagram showing our hydrogen chloride generation system in greater detail.

While our invention is applicable to a wide variety of aluminum chloride-hydrogen chloride hydrocarbon conversion processes, it will be described in connection with a process for isomerizing a light naphtha consisting essentially of paranic hydrocarbons of the butane to hexane boiling range. Referring to Figure 1, a virgin naphtha charging stock is introduced by pump I through heat exchanger I I to fractionating tower I 2 which is provided with suitable heating means I3 at its base and which is operated under such conditionsthat heptanes and heavier hydrocarbons are removed from the base through line I4. A side stream consisting essentially of C5 and Cu hydrocarbons may be withdrawn by pump I5 lthrough heater I5 and then split into two streams, the small stream passing by line lI1 to slurry tank I8 and the large stream passing by line I9 to hydrogen chloride absorber 20. Where the make-up aluminum chloride is slurrled with recycle material the valve in line I1 may be closed and all of the charging stock may be passed to the absorber.

Overhead from fractionator I2 is withdrawn through line 2I and cooler 22 to reflux drum 23 from which uncondensed gases may be vented through line 24. When a side stream has been withdrawn the reilux condensate will consist essentially of butane which is withdrawn from the base of the drum by means of pump 25. A portion of this reflux condensate may be returned through line 25 to serve as reilux in the top of tower I2. Reflux condensate from this source may be introduced through line 21 to line I1 or through line 28 to line I9 or it may be passed to line 29 to an absorber system or withdrawn through line 30 for use or storage elsewhere in the hydrocarbons may be withdrawn4 from the through line 3|. The hydrogen chloride absorber 20 is preferably operated under a superatmospheric z pressure 5 which may range from about 50 to 350 or more pounds per square inch but which is preferably in the general vicinity of 200 pounds per square inch. A gaseous stream containing hydrogen chloride is introduced at the base of this absorber through line 32 and make-up hydrogen chloride is introduced at the base of this absorber through line 33. Unabsorbed gases chiefly hydrogen, methane, ethane, etc., leave the top of the absorber through line 34 and may be vented l5 from the system through line 35 or introduced through line 36 together with additional hydrogen containing gases from line 31 into the base oi absorber 38, a suitable compressor 39 being employed for this purpose. introduced by pump 40 and line 4I to the Itop of absorber 38. This absorber may be provided with suitable baiiies or bubble plates and it may be operated at a temperature of about 100 F. and a pressure of about 900 pounds per square inch. Gaseous hydrocarbons are absorbed and introduced through line 42 and' pressure reducing valve 43 into separating chamber which mayv ,operate under about 35 pounds pressure. Hydroncarbongases may be purged from the system through line 45 and the'butane from the base 'of the separator may be returned through line 4S, pump and line 4I back to the top of the absorber. Hydrogen leaves the top of the absorber through line 41.

The charging stock-hydrogen chloride solution from the base of absorber 20 is pumped by pump 48 through heater 49 and lines 50 and 50a into isomerization reactor 5I. Hydrogen from line 41 or from outside source 52 is introduced by com- 40 pressor 53 either into line 50 or directly into reactor 5I. About 100 to 300, for example about 200 cubic feet of hydrogen is charged to the reactor per barrel of light naphtha charged thereto. Make-up aluminum chloride in the form of A a slurry, solution or complex is introduced into reactor 5I either from slurry tank I8 by means of pump 54 and line 55 or from other parts of the system through line 58.

The reactor contains a large amount of aluminum chloride catalyst material which is usually in the form of an aluminum chloride hydrocarbon complex. The charging stock passes upwardly through this catalyst material in iinely divided dispersed phase at a space velocity of about .2 to 4 volumes of liquid charging stock per hour per volume of catalyst material. The temperature in the reactor is within the range of 100 to 400 F. and is usually in the general vicinity o! 250 F. The pressure in the reactor is in the range of 500 to 1500 pounds per square inch and may be about 850 pounds per square inch. Reaction products are withdrawn from the top of reactor 5I through lines 51 and 53 to, warm settler 58 and thence through line 5l, cooler 5I and pressure reducing valve 62 to cool settler 53. Gases leave the top of the cool settler through line 64 and are returned by line 32 to hydrogen chloride absorber 20.

Clear 'I product liquids leave the cool settler throughgline 85 and are introduced by pump 45 into hydrogen chloride stripper column 81 which is provided with a suitable heating means 58 at v its base. The overhead from this stripper may be passed through line 89 to line 32 for recycling or may .be passed through cooler 10 to reflux Butane from line 29 is' associ-1 drum may either be returned by line le for use as 1 reflux in the top of the stripper or may. be withdrawn through line 1B. The product from line le contains isobutane and when it is passed to an aluminum chloride alkylation system it is unnecessary that dissolved hydrogen chloride -be removed therefrom. Stripper tower 81. may thus function both as a hydrogen chloride stripper and as a stabilizer tower.

Liquid products from the base of tower 61 .are passed directly by line l5 or through cooler 'I8 to caustic scrubber and Wash tower 11. Caustic may be introduced through line 18 and the water through line 19. 'I'he wash water may be trapped out above the caustic inlet or the water and caustic may both be removed from the base of the tower through line 80.

The neutralized and water washed product is withdrawn from the top of the wash tower through line 8l and it may either be` withdrawn from "the system through line .82 or passed through line 83 and heat exchanger 84 to stabilizer or drawnas a line 9|.

isomerization system hereinabove described. A

` part of this make-up hydrogen chloride may be recovered from spent sludge in recovery drum |05 by' adding sulfuric acid or water from line IH to hydrolyze such' sludge. If water is employed it should be used in less than stoichiometric amounts in order that the recovered hydrogen chloride may be anhydrous! Sulfuric acid will produce more anhydrous hydrogen chloride from' the sludge and should, therefore, be used particularly in reneries which are provided with ments of theisomerization process and an outstanding feature of our invention is theuse of a high pressure hydrogenchlorlde generator as an integral part of our vunitary isomerization system. Such a generator is schematically illusltrated in Figure 1 by pressure chamber |20 into which a. .chlorine supplying reagent is introduced through une m and e hydrogen supplying reagent is introduced through line |22. By-prodline '88 or returned through lines 89 and 90 to 'slurry tank I8. A light isomate may be withside stream from tower 85 through Overhead from theI stabilizer is passed through cooler 92 to reiiux ldrum s3 from which gases may be vented through line 96. A portion of the reflux' may be returned by pump 95 through line d@ to the top of the stabilizer and a light fraction consisting. for example, chiefly of isobutane ucts are removed from this pressure chamber throughv line |23 and thegenerate'd hydrogen chloride is introduced dietlyfrom the topof 5 this-chamber through line 23 to the hydrogen vchloride absorber 20. Since generator |20 opertraneous gases from the generated hydrogen chloride because theseI gases will be removed may be withdrawn from the system through line di.

Instead oi employing 'a single reactor we may employ a multiple reactor system. Thus chargi ing stock with absorbed hydrogen chloride may be introduced through line 50h to reactor bib and make-up catalyst may be added to this reactor through line 55o `or through line ln Alternatively, the products leaving thev top ci from the system with purge gases leaving the top of the absorber 2d.

Pressure vessel |26 may be an acid. resistant kettle into which sodium chloride is introduced through line 52| and sulfuric acid is introduced chloride recovery drum itt. Catalyst may be withdrawn from the base of reactor di by pump ide Yand either withdrawn from the system through line it?, passed to reactor Eh through line Silit or passed 'to the hydrogen chloride recovery drum through lines it@ and idd.

Settled catalyst material from settler be may ce passed through lines il@ and @d to slurry tank |53 or through 'lines i ii and ddh to reactor chamber ein or through lines M2 and be to reactor di. Precipitated catalyst material from cool settler d3 may be pumped as a slurry by pump lie through lines Die and s@ to slurry tank i3 or through lines H5 and 65o to reactor bib or through lines! it and 56 to reactor 5|.

Our invention is primarily concerned with the supplying of make-up hydrogen chloride to the through line |22. Instead of employing sodium chloride we may employ aqueous hydrochloric acid (for example 22 muriatic acid). Generators of this type are already known to. the 'irt and no invention is claimed in such generators per se. Ourfii'rvention contemplates the operation oi such generators asa unitary part .of the Av preferred hydrogen chloride generator for:

use in this system is schematically illustrated in Figure 2; In this' system generator |2ii'is' a glass lined or corrosion resistant pressure vesselv which may be provided with a jacket |24 intol which steam or other heatexchange uid may be introduced through line m5 and .trono which some cases it may henecessary or desirable to ser] |20.

blow it 'with air or pass it through a-salt drum for removing water before charging it into chamorine is charged to-this chamber from a pressure drum or by means of pump4 |28 through lines I 29 and ill until the pressure in the chamber is slightly higher .than the pressure in absorber 20. When this pressure'is reached 'the valve in line Ill is opened-so that the entrap |32, cooler |33 and separator |34 and thence through line 33 directly into the base of absorber 20. Baiiles |35 may be employed in the upper part of spray trap |32 and suillcient cooling may be employed in cooling coils |33 to insure 5 the removal of any normally liquid hydrocarbons or chlorinated hydrocarbons from the gas- -eous stream. Liquids may be removed from the base of spray traps |32` through line |36 and from the base of separator |34 through line |31 10 and may be withdrawn from the system through line |38.- Any gaseous impurities in the generated hydrogen chloride will be eliminated from the system by vent gases leaving the top of absorber 20.

After the oil or wax has been chlorinated to the required extent the valve in line |3| may be closed and the chlorinated -product may be withdrawn from chamber through line |23. We may, however, introduce the chlorinated Wax by 20 means of pump |39 through line |40 to a second pressure vessel |4| which is also jacketedfor temperature control. Naphthalene may be added to chamber |4|' through line |42 and aluminum 'l chloride or other catalyst material may be added to this vesselvfrom hopper |43. This pressure, vessel may be provided with a rapid stirrer |44 driven by a suitablel motor |45 and a condensa.-

tion reaction may then be effected in reactor |4| as described, for example, in United States reaction vessel.' Alternatively, one reaction vessel `may be on-stream While'the other is being.

charged, emptied or cleaned. A continuous chlorine generation system may be employed instead of the batch systems hereinabove described. Other modications and equivalents` will be apparent to those skilled in the art from the above detailed description.

. It should be pointed-out that a considerable excess of hydrogen chloride may-be tolerated in the isomerization system and that this hydrogen chloride is merely recycled from the product separation step back to the absorber. The amount 55 of hydrogen chloride introduced into the isomerization reactor may range from 'abouty 3% to 10% or more by weight based on light naphtha charged. Thus it is not essential that the makeu p hydrogen chloride be added through line 33 60 at a uniform rate and one of the features of our process is the fact that the isomerization system,

is not disturbed by interruptions in the supply of make-up hydrogen chloride or bythe periodic injection of relatively largeamounts oi' make-up 65 hydrogen chloride. The isomerization system acts as a storage reservoir to accommodate fluctuations in the production of hydrogen chloride and its rquirementsare adequately met if the hydrogen chloride concentration in the oi1leav 70 ving absorber 20 does not fall materially below about 3%.

It will thus be seen that we have not only solved the problem of hydrogen chloride disposal in a chlorination and condensation reaction but we have provided a unitary combination of such system with a light naphtha isomerization system. Our invention is not limited to any of hydrogen chloride, the improved method of operation which comprises introducing a hydrocarbon charging stock at the upper part of an absorption zone at a presure within the general vicinity of 50 to 350 pounds persquare inch, .introducing a heating the withdrawn solution and contacting it with said catalyst for eiecting a conversion to produce saturated parafilnic hydrocarbons of branched-chain structure, separating from said products a gas stream containing hydrogen chloride and gaseous impurities less soluble in the charging stock than hydrogen chloride and returning said stream from introduction at said low point in said absorption zone, separately generating make-up hydrogen chloride containing gaseous impurities less soluble in the charging stock than hydrogen chloride under superatmospheric pressure, introducing said generated make-up hydrogen chloride and'gaseous impurities as'a gas stream at a low point in saidabsorption zone directly from said generating step without compression. and without liqueiaction, and

withdrawing from the top oi said absorption zone unabsorbed gaseous impurities introduced thereto With'said hydrogen chloride streams.

2. 'I'he method of claim 1 wherein said gaseous impurities are hydrogen and hydrocarbon gases which method includes the further steps of introducing gases from the top of said absorption zone into a low point ot a second absorption zone operated at higher pressure, introducing absorber fliquid at an upper point in said second absorption zone for r noving hydrocarbon impurities,

withdrawing hy ogen from the top oi.' said second absorptionV zone and, introducing said hydrogen into said conversion zone.

hydrolyzing relatively spent catalyst material from theonverslon step.

' LT1 WAYNE A. PROELL.

L FRANK K. OVITZ. 

